Telephone receiver and similar sound-producing device



2 Sheets-Sheet 1 Ww. A. H ....v.

Ar hm" F3. Youn by His Attorney.

July 20,1926.

. A.' P. YOUNG TELEPHONE RECEIVER AND SIMILAR SOUND PRoDUcINE DEvIcE Filed may 19. 192:',-

9 f A. P.VYOUNG' j 'TELEPHONE Rfzcmvfm AND IHSIIM'ILAH spUND APmMJ'UcING DEvIB Film-May 19. `15:23 2 sheets-skelet 2' .l lfm/@futon v Arthur* p. by

Youn f His Attorney.

2B netic circuit.

` Patented .lilly 20, i

UNITED STATES TENT ARTHUR 15. YOUNG, or KENILWORTH, ENGLAND, AssIGNoR `To entrenan ELECTRIC A comPANY, A conroaarion or NEW Yoan.

TELEPHONE REEIVER AND SIMILAR SOUND-PRODUCING DEVICE.

Application ledMay 19, 1923, Serial No. Se, and in England -May 20, 1922.

My present invention relates to telephone receivers and similar sound producing de vices of the type in which a coil or coils mounted upon the pole pieces of a magnetic 5 circuit, actuate a diaphragmvand vvibrate it according to the fluctuations of en rrent through the coil or coils to produce sound Waves.

The object of my inventionv is to provideY device of 1o an improvedconstruction for a this character. f l

In carrying out my invention I mould a portion or thevvholel vof the magnetic material constituting the magnetic-circuit of the instrument in a moulded composite insulating material, such as plastic india rublber or synthetic resin. Metal inserts, such as the terminal posts'where the 'ends of the exciting coils are united to the leading-in 2t conductors and the stud Where connection is made between thetelephone receiver and the head band or other supporting member, mayalso be moulded into ,the insulating material at the same' time as the parts of the mag- Preferably the moulded material is formed so as to retain some or all ofthe above-mentioned parts and also constitute the casing of the instrument.

The magnetic circuit preferably comprises laminated or solid pole pieces moulded in the moulded composite insulating material and a permanent magnet preferably of cobalt steel is either moulded into the material in the same plane as the `pole pieces with lits poles adjacent to pole pieces or is moulded laterally of the pole pieces. In some cases two permanent magnets may be employed, one on each sidewof the plane of the Jpole pieces, and arranged so that their polar extremities are Iadjacent the sides of the pole pieces. Instead 'of moulding the magnet, or magnets ,into the materia-l a recess or recesses may be moulded in the material and "the magnet or magnets may be wedged in the recess or recesses.

In the preferred construction of a teleeceiver according to my invention I pole pieces and metal inserts into uded composite insulating material c to form a casing, and at the same time 1- mould a straight slot or recess at ene ,side of the pole pieces slightly larger than e straightbar magnet which, after and hardening by means of heat, in the recess, a wedge is sive, represent modifications of my driven in between the magnet and the outer wall of the recess so as to force theA poles of the magnet into good contact with the pole pieces. The coils arethen mounted on the pole pieces and the coil terminals are se- 6o cured to the terminal screws and the leading-in conductors on the side of the pole pieces opposite to the magnet. A diaphragm, of stalloy, for example, is then, placed over the casing and held in position by the usual screwed cover with an openingr in the center.

Other ,forms of magnetic circuit and arrangement of pole pieces and magnets falling within the scope of my invention are hereinafter set fort My invention will be more fully described in connection with the accompanying drawings, in' which Figs. 1, 2 and 3 represent 'the preferred form of construction embodying my invention. Fig. 2 is a plan view of a telephone receiver with the cover plate and diaphragm removed. Fig. 1 is a sectional elevation about the line l-l of Fig. 2, and Fig. 3 is a sectional elevation about the line 80 3--3 of Fig. 2. Fig.` 4 is a diagram of the electrical connections. Figs. 5 to 10, incluinvention in which Figs. 5 to 9 illustrate different methods of forming and mounting the magnetic structure; Fig. l0 being a transverse sectional elevation of Fig. 9. y

Similar. reference numerals are used throughout to denote^`like parts.

Referring now to Figs. l, 2 and 3, lami- 90` nated. sections of softiron l constituting pole pieces are moulded into a moulded composite insulating material 2v such as plastic india rubber or bakelite. These lamina- 1 tions may be held together by rivets?, or they may simply be drilled transversely in order that the insulating material may iiow into the drilled holes so as firmly to retain the laminations in position. In this case a suitable spacing piece t'may be clamped to 10G the pole pieces l to hold them in position while the insulating material is being cast around them. The pole pieces may in some cases be solid instead of laminated. At the same time a metal plug 5v is preferably 3.05 moulded into the bottoml of the casing or it may be formed integrally with the spacing member et. This plug` is provided with a threaded hole 6 which is adapted to receive the corresponding threaded stem of the ear- M* piece support. On one side of the pole piece and adjacent the base limb there. is left a substantially rectilinear slot or recess 7' adapted 'to take a. short bar magnet 8, preferably a cobalt steel magnet. The side of the slot away' from the pole piece may `be filled with moulded insulating material` but preferably a fiber or similar wedge l) is driven in to press the ends of the bar magnet firmly against the base ot' tliepole pieces 1. .The free ends ofthe pole pieces 10 are narrowed as shown in order to take the standard size coils 1l and are of a height slightly lessthan that of the side 12 oi" the casing. The upper rim of the casing is screw-threaded externally as shown at 13 to engage with an lapertured cap or cover 14' made preferably of similar material, and the diaphragm 15 has its rim secured between these two members. In order to adjust the distance of the diaphragm trom the tips of vthe pole piecesv suitable packing rings may be inserted between thc. edges of Vthe dia` phragm and the upper rim of the casing 2.

On the opposite side ot the pole pieces from that on which the magnet is located', a cavity 16 isfprovided to take the conducting leads 17,` the ends of which are held by terminal screws 18 engaging with a corresponding metal-insert which is moulded into the composite material. The ends of the coils 11 are secured by .solder or the like to metal washers 19 which are held in electrical conection with the ends-of the conducting leads 17 by the screws 18.` In the dia gram of electrical connections shown in Fig. 4, it will be seen that the coils are so arranged that when the current flows in a given direction Aone pole piece will be of n'orth polarity While the other pole piece is of south polarity. Combining this polarity with the polarity due tojthe permanent magnet 8, it will be seen that the fluctuations of current through the coils 12 will' serve alternately to weaken and strengthen the flux passing from one pole piece to the other pole piece through a portion of the diaphragm, causing the latter to vibrate.

rIlhe design of telephone receiver shown in Figs. 1, 2 and 3 manufactured as above described has been found to give very sensitive operation when used with radio receiving sets. This may be partly due to the rigidity of the mounting of the pole pieces and partly to the provision of the chamber between the diaphragm and the flat surface from which the pole pieces project. As will be seen from Fig. 3 this surface is uniform except for the polar projections-and the semi-circular recess where the leading-in conductors enter the casing.

It will be obvious that in cases where a stronger exciting torce is required a.l slot may be provided for holdinr a second magnet adjacent the base limbs of the pole pieces instead of the cavity 16 previously described; in which case the conducting leads 17 would be secured by the screws 18 engaging withmetal plugs moulded into the bakelite between one of the slots 7`and the sido of the casing 2.

ln the construction shown in Figs. 5 to a single bar magnet 8 is provided and mounted uponthe ends thereof are the pole pieces 1, the pole pieces and the magnet now being in the sameJ plane. In Fig. 5 the magnet is retained in position by means of a screw 20 securing it to the insulating material between the pole pieces, and the ends ot' the bar magnet and pole pieces are sloped ofi' at an angle so as `to lit together like a Window frame. In Figs. 6 to 8, an insulating material such as plastic india. rubber, bakelite, etc. is moulded around the outside of the bar magnet. In Fig. 6 the lower ends ofthe polar laminations 1 are provided with a recess 21 which engages with the correspondingly shaped end of the bar magnet 8. In Fig. 7 I have indicated an arrangementwhereby any of the constructions illustrated may be combined with projecting pieces'28 formed in the magnetic circuit to provide a shunt path for the flux` ina manner that is well known per se, and in both Figs 7 and 8 mild steel screws are employed for securing the pole pieces to the magnet. In Figs. 9'and 10, a U- shaped magnet is used, the limbs thereof being preferably ollset towards each other near the yoke and parallel at their tree ends. Holes 24.- are provided transversely through this magnet and the composite material penetrates' these holds during the moulding operations and thereby rigidly holds the magnet in position. The free ends of the magnet are preferably cut, leaving rectangular pole ieces of uniform cross-section adapted to ta e the standard coils 11. These pole pieces may also be slotted to reduce eddy currents. In Fig. 10 it will be noticed that a considerable portion of the insulating material has been omitted and instead of the watch type telephone receiver shown in Fig. 1, we have .a flat circular form with a diametrically projecting portion 25 moulded around the yoke of the magnet 23. j

While in all the gures the lfree ends of the pole pieces are indicated as consisting of a Vcut away rectangular portion cylindrical pole pieces. either straight or slightly tapering may ne used if preferred to take similarly arranged coils. In all cases, by providing the fiat surface 27 on theipole pieces a suitable bed will be provided upon which vthe coils may rest.

lVhat I claim as new and desire to secure by Letters Patent ofthe United States, is c- 1. The combination in a telephone receiver of a body of moulded composite insulating material, a pair of pole pieces having coil holding portions which extend lupwardly above said body of insulating material and.v

odset portions eXtendin parallel to said coil holdingl portions an said body of insulating material, and `a permanent magnet which is held in intimate contact with said pole pieces by said body of insulating material'. v 2. ln a telephone receiver, a pair of pole pieces, a casing moulded about the pole pieces and adapted to hold them in position, said` coil holding casing being provided with a substantially rectillnear regess adjacent one side of said pole pieces, a permanent magnet mounted 1n said recess, and means for holding the permanent magnet in intimate contact with said pole pieces. v

3. The Icombination in a telephone receiver of a body of moulded composite insulating material, a pair of pole pieces having portions which extend upwardly above sai body of insulating material,

horizontallyextending portions which are embedded in said body and downwardly extending portions which are also embedded therein, and a permanent magnet which is held in intimate contact .with said pole pieces by said body of insulating material.

4. The combination in a telephone receiver of a pair of laminated pole piecesv which are Amoulded in a body of mouldedcomposite insulating material, the laminations of said pole pieces being held in desired space relation by means of the insulating material, and a permanent magnet which is held with its poles in intimate con- .tact with said pole pieces.

downwardly linto j 5.'ln a telephonereceiver, a pair pf pole pieces, a casing moulded abo-ut the pole pieces and adapted to hold them in position, said casing being provided with a`substantially rectilinear groove adjacent one side of saidpole p1ece s,a permanent magnet vmounted in said groove and adapted tov contact with `said pole piece's,and means for'adjusting the contact between the pole pieces and permane-nt magnet.

6. In a telephone receiver, a pair of pole pieces,a casing mounted-about said pole pieces and adapted to hold them in posi-` tion, said casing being provided with a rectilinear groove adjacent one side of said pole pieces, a permanent magnet loosely mounted in said groove and adapted to'contact with said pole pieces, and means for holding the 'permanent magnet in intimate Contact with holes through the individual laminations' and a body of moulded composite insulating material which fills the holes in the laminations, and holds the laminations and pole' pieces in a desired space relation.

In witness whereof I have 4hereunto set my hand this 17th day of May,'1923.

. ARTHUR P. YOUNG. 

